The present invention relates to a control device for a transmission which is shiftable in a selected one of a plurality of shift patterns.
A control device is known wherein a shift pattern is switched automatically one after another, which control device is shown, for example, in Nissan Service Manual No. 484 (P47, P64) issued on June 1983 by Nissan Motor Company Limited (see pages 225 and 226). More specifically, a standard shift pattern and a power shift pattern are provided and one of them is automatically selected which is fit for the current running conditions. The standard shift pattern is fit for ordinary economical running, while the power shift pattern is fit for hill-climbing and rapid acceleration. Normally the standard pattern is selected, and it is switched to the power pattern when an accelerator pedal is depressed at a rate greater than a predetermined value. Such a predetermined value is set appropriately in accordance with a vehicle speed and a throttle opening degree at which the depression of the accelerator pedal commences. With the power pattern selected, if the opening degree of the throttle valve is returned to 1/8 of the fully opening degree, the standard pattern is selected again.
However, this known control device for transmission poses a problem that the power shift pattern is not selected though it is desired at so-called stall start-up (i.e., a start-up of the vehicle after a brake is released under conditions where the throttle valve is fully opened or almost opened with the brake activated). This is because the speed at which the accelerator pedal is depressed will not exceed the predetermined value after the throttle opening degree has already reached its fully opened position and thus even if the driver wishes rapid acceleration, the power shift pattern is not selected.
An object of the present invention is to provide a control device which is free from the above mentioned problem.